Hydrostatic system for overhead crane trolley

ABSTRACT

An oil filled hermetically sealed tank reservoir is supported overhead at the trolley level and is connected via conduit to the trolley side truck which includes enclosed portions forming an integral part of the reservoir. The tank contains essentially all hydraulic and electrical operating components as well as the high pressure hydraulic piping for operation of the hoisting and traverse functions of the overhead crane trolley. Oil within the tank is free to circulate between the tank and the enclosed portion of the trolley side truck making full use of peripheral wall surface to dissipate heat for maintaining temperature of the oil within allowable limits.

United States Patent 1191 Johnston et al.

[ 1 Sept. 23, 1975 HYDROSTATIC SYSTEM FOR OVERHEAD CRANE TROLLEY [75]inventors: Robert R. Johnston, Muskegon; Walter Arnold Paulssen, SpringLake, both of Mich.

[73] Assignee: Dresser Industries, Inc., Dallas, Tex.

[22] Filed: Apr. 24, I974 [21] Appl. No: 463,471

[52] US. Cl. 212/26; 60/404; 60/D1G. 10 [51] Int. Cl. B66C 17/00 [58]Field of Search 212/10, 11, 26, 32, 124;

60/477, 403, 404, DIG. 10; 254/150 FH; 303/10; 188/170 [56] ReferencesCited UNITED STATES PATENTS 2,631,431 3/1953 Grebe 60/477 2,940,6086/1960 Underwood et al. 212/124 3,035,414 5/1962 Smith 254/150 FH3,279,172 10/1966 Kudo et al. 60/484 Gourlay et al. 60/463 Terry 60/398[57] ABSTRACT An oil filled hermetically sealed tank reservoir issupported overhead at the trolley level and is connected via conduit tothe trolley side truck which includes enclosed portions forming anintegral part of the reservoir. The tank contains essentially allhydraulic and electrical operating components as well as the highpressure hydraulic piping for operation of the hoisting and traversefunctions of the overhead crane trolley. Oil within the tank is free tocirculate between the tank and the enclosed portion of the trolley sidetruck making full use of peripheral wall surface to dissipate heat formaintaining temperature of the 011 within allowable limits.

3 Claims, 5 Drawing Figures US Patent Sept. 23,1975 Sheet 1 of33,907,120

US Patent Sept. 23,1975 Sheet 2 of3 3,907,120

FIG. 3

FIG. 4

US Patemt Sept. 23,1975 Sheet 3 of3 3,907,120

FIG. 5

HYDROSTATIC SYSTEM FOR OVERHEAD CRANE TROLLEY CROSS REFERENCE TO RELATEDAPPLICATIONS Application Ser. No. 463,500 entitled Crane Bridge Trolleyco-filed herewith in the name of Paulssen and Chapin.

BACKGROUND OF THE INVENTION 1. The field of art to which the inventionpertains includes the art of Traversing Hoists" and more particularly tohydraulic actuating systems therefor.

2. Various forms of hydraulic operated cranes have been developed overthe years, as for example disclosed in US. Pat. Nos. 497,216; 2,984,191and 2,906,143. Despite existence of the technology, the hydraulic cranehas not met with any large measure of commercial success, at least noton a commercial scale even remotely comparable with those cranesutilizing components that are driven electrically. In a typical priorart installation for a hydraulic actuated crane trol ley, long exposedhydraulic conduits extend about the trolley frame to each of theindividual components operable thereby. While various objections tothose systems are known to exist among crane customers as, for examplehigh noise level, etc., reluctance to purchase is principally attributedto a dislike for the hazard of likely oil leakage from burst lines orpoor joints in the system and the combustion risk contemplated by suchleakage. The objections can be readily reconciled such that when given achoice the customer would just as soon avoid the problem.Notwithstanding recognition of the commercial deterrents associated withhydraulically operated crane trolleys of the prior art, a ready solutionhas not heretofore been available.

SUMMARY OF THE INVENTION This invention relates to an improved systemfor operation of overhead crane trolleys and more particu larly to animproved hydrostatic system therefor. Unlike previous hydrostaticsystems utilizing long exposed conduit having a multiplicity of jointsfor supplying the individual hydraulic components remotely scatteredabout the crane trolley, the system in accordance herewith completelyencloses and submerges all high pressure hydraulically operatedcomponents and all high pressure piping that operationally control thehoisting and traverse functions of the crane. Enclosure of thecomponents and piping is within a hermetically sealed oil filled tankreservoir supported overhead at the trolley elevation and which utilizesits available exterior walls as a thermally conductive surface by whichtemperature of the contained oil is maintained within allowabletemperature limits. Within this arrangement, a novel holding brakemechanism is provided by which to operate the brake normally associatedwith positioning and holding of the crane hook. By virtue of thehydrostatic system being almost entirely contained within a sealed tankreservoir, the previous problems of conduit dripping and/or combustionhazards have been substantially, if not completely, eliminated.

It is, therefore, an object of the invention to provide an improvedsystem for operation of an overhead crane trolley.

It is a further object of the invention to provide a novel hydrostaticsystem for operation of an overhead crane trolley able to substantially,if not completely, eliminate the prior hazards ofoil leakage previouslyassociated with similar purpose systems of the prior art.

It is a still further object of the invention to effect the foregoingobjects with a hydrostatic system operably controlling both the hoistingand traverse operations of 'an overhead crane trolley with anarrangement that is economically virtuous as compared to such similarpurpose constructions of the prior art.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view, partially insection, of an overhead crane trolley employing the hydrostatic systemin accordance herewith;

FIG. 2 is an end elevation;

FIG. 3 is a side elevation as viewed substantially along the lines 3-3of FIG. 1;

FIG. 4 is a side elevation, partially in section, as viewedsubstantially along the lines 4-4 of FIG. 1; and

FIG. 5 is a schematic diagram of the operable hydraulic circuitryemployed herein.

Reference is now made to the drawings in which there is illustrated anoverhead, top running crane trolley designated of a type with which theinvention hereof can be utilized. Crane trolley 10 is more completelydisclosed in the above mentioned copending application cross referencedherewith. Briefly, trolley 10 is a 3-point support trolley adapted fortraversal operation on parallel rails 12 and 14 in turn supported onbridge girders (not shown). Comprising the trolley is a truck thatincludes a partially enclosed frame 21 supported on rail 14 by means ofa drive wheel 26 and a longitudinally displaced trailer wheel 22.Laterally extending in a T-like formation from a support in frame 21 isa cylindrically elongated rope drum 32. The distal end of drum 32 issupported within the hub of a third fiangeless wheel 36 adapted fortraverse movement over guide rail 12. Formed in the periphery of thedrum are right hand rope guides 38 and left hand rope guides 40 betweenwhich the drum supports rope sheave's 42. Beneath sheaves 42, reevedrope 43 supports a block 44 carrying a load hook 46. Rotation of thedrum effects required raising and lowering of load hook 46 while aspring biased holding brake mechanism 50 is operative as will bedescribed for securing the load hook at any set position.

Comprising the hydrostatic system for operating trolley 10 in accordanceherewith is an electric motor 52 operably attached at opposite ends tohydrostatic pumps 54 and 56. All of these components are contained in anelongated hermetically sealed tank 58 comprised of side, top and bottomwalls 62 formedof corrugated steel approximately /8 inch in thickness.The tank is supported at or about the trolley elevation and togetherwith the enclosed portion of frame 21 forms the reservoir for system oil60. Exterior wall surface of the reservoir is predetermined to at leastprovide adequate heat transfer sufficient to conductively maintaintemperature of oil within allowable limits not to exceed about 180F.Each of the motor and pumps are of the type commercially available fromSundstrand Hydro-Transmission of Ames, Iowa. The level of oil 60 withintank 58 is at least sufficient to submerge the aforementionedcomponents. Volume output of pumps 54 and 56 and the direction ofhydraulic flow to hydraulic motors 64 and 66 are individually controlledelectrically by remotely located joy sticks 65 and 67 through whichcrane trolley operation is governed. Joy stick 67 acts to operate thehoisting functions while joy stick 65 acts to operate the traversefunctions.

Incorporated into the operation hereof are three individual brakingsystems for safety and control of the hoisting operation. The first ofthe systems is the dynamic braking hydraulically afforded by the closedhydraulic loop formed by conduits 76, 78 and 80 between motor 66 andpump 56. Being a closed loop, inoperability or significantly curtailedoperability of the pump inherently brakes the system. The second brakingsystem is provided by the pilot operated counterbalance valve 70connected between conduit 78 and 80 serving to trap oil in conduit 80between it and the load side of hoist motor 66. When oil is trapped inthat manner, the hoist motor is prevented from rotating in the loweringdirection until pilot pressure is applied from pump 56 via conduits 76and 82 for releasing counterbalance valve 70. Providing the thirdbraking system is a spring set normally closed, shoe brake 50 having ahydraulic operating cylinder 84. Cylinder 84 is in turn supplied viaconduit 88, solenoid valve 90, conduit 92 and flow control valve 94 by acharge pump 86, integrally part of hoist pump 56. In the absence of orloss of charge pressure, line 92 is open to the tank and spring 74operates to close brake 50. Solenoid 90 is energized by controller 67being moved slightly toward hoist or lowering position to actuate brakecylinder 84 for opening brake 50 in opposition to spring 74. Flowcontrol valve 94 operates to introduce a predetermined time delay sothat under normal operation the hoisting and/or lowering motion isarrested before closing brake 50, thereby avoiding undue wear on thebrake lining.

By the above description, there is disclosed a novel system foroperation of an overhead crane trolley in which all the operatingcomponents are hydraulically actuated and all are submerged in ahermetically sealed tank supported at the trolley level. The tankcomprises the oil reservoir and by its enclosing walls providessufficient exterior surface area for conductively cooling of the oil inorder to maintain oil temperature within allowable limits. By virtue ofthe entire drive system being submerged, the noise level normallyassociated with high pressure hydraulic systems of the prior art issubstantially if not completely eliminated. At the same time, the systemis able to operate the holding brake with a time delay that sets afterall motion of the load hook stops thereby preventing excessive wear onthe brake shoes as would otherwise be encountered. With the predominanceof hydraulic piping and all high pressure piping likewise beingcontained within the oil tank reservoir, the entire system issubstantially isolated against the possibility of hydraulic spraytypical of failure occurring in a hose or other hydraulic pressureconduits of the prior art.

Since many changes could be made in the above conbodiments of thisinvention could be made without departing from the scope thereof, it isintended that all matter contained in the drawings and specificationshall be interpreted as illustrative and not in a limiting sense.

We claim:

1. A hydrostatic system for operating an overhead crane trolleycomprising in combination:

a. a crane trolley supported overhead and operable when actuated toeffect traversal and hoisting functions;

b. a sealed tank supported at the general elevation of the crane trolleyand adapted to contain a fill of hydrostatic oil;

c. a plurality of components supported in said tank adapted to besubmerged beneath the oil level thereof, said components including:

1. an electric motor;

2. a pair of pumps operably connected to said motor;

3. a first hydraulic motor connected to one of said pumps and adapted toactuate the hoisting function of said trolley; and

4. a second hydraulic motor connected to the other of said pumps andadapted to actuate the traversal function of said trolley;

d. control means to independently actuate said first and secondhydraulic motors for independently effecting operation of theirrespective actuating functions;

e. a plurality of braking systems operably controlled by said tanksupported components and operably interacting with each other, one ofsaid braking systems being hydraulically responsive to forming of an oiltrap thereto, another of said braking systems being dynamicallyresponsive to reduction in hydraulic supply pressure within a closedhydraulic loop thereto, and still another of said braking systems beingmechanically operable and comprising a pair of brake shoes movable intoand out of braking relation with a braking surface and a hydraulic unitoperably connected to said brake shoes and effective when energized toactuate said shoes toward said braking relation; and i f. flow controlmeans introducing a controlled time delay in energizing said hydraulicbrake unit following occurrence of events requiring said mechanicalbraking system to be actuated.

2. A hydrostatic system according to claim 1 in which the exterior wallsof said tank are thermally conductive to afford conductive cooling ofsaid oil fill.

3. A hydrostatic system according to claim 2 in which said trolleyincludes a frame support at least a portion of which is enclosed and islocated juxtaposed to said tank and the walls of said enclosed frameportion to- 'gether with the walls of said tank provide a predeterminedsurface area for conductively cooling said oil fill to within apredetermined limit of temperature rise.

1. A hydrostatic system for operating an overhead crane trolleycomprising in combination: a. a crane trolley supported overhead andoperable when actuated to effect traversal and hoisting functions; b. asealed tank supported at the general elevation of the crane trolley andadapted to contain a fill of hydrostatic oil; c. a plurality ofcomponents supported in said tank adapted to be submerged beneath theoil level thereof, said components including:
 1. an electric motor;
 2. apair of pumps operably connected to said motor;
 3. a first hydraulicmotor connected to one of said pumps and adapted to actuate the hoistingfunction of Said trolley; and
 4. a second hydraulic motor connected tothe other of said pumps and adapted to actuate the traversal function ofsaid trolley; d. control means to independently actuate said first andsecond hydraulic motors for independently effecting operation of theirrespective actuating functions; e. a plurality of braking systemsoperably controlled by said tank supported components and operablyinteracting with each other, one of said braking systems beinghydraulically responsive to forming of an oil trap thereto, another ofsaid braking systems being dynamically responsive to reduction inhydraulic supply pressure within a closed hydraulic loop thereto, andstill another of said braking systems being mechanically operable andcomprising a pair of brake shoes movable into and out of brakingrelation with a braking surface and a hydraulic unit operably connectedto said brake shoes and effective when energized to actuate said shoestoward said braking relation; and f. flow control means introducing acontrolled time delay in energizing said hydraulic brake unit followingoccurrence of events requiring said mechanical braking system to beactuated.
 2. a pair of pumps operably connected to said motor;
 2. Ahydrostatic system according to claim 1 in which the exterior walls ofsaid tank are thermally conductive to afford conductive cooling of saidoil fill.
 3. A hydrostatic system according to claim 2 in which saidtrolley includes a frame support at least a portion of which is enclosedand is located juxtaposed to said tank and the walls of said enclosedframe portion together with the walls of said tank provide apredetermined surface area for conductively cooling said oil fill towithin a predetermined limit of temperature rise.
 3. a first hydraulicmotor connected to one of said pumps and adapted to actuate the hoistingfunction of Said trolley; and
 4. a second hydraulic motor connected tothe other of said pumps and adapted to actuate the traversal function ofsaid trolley; d. control means to independently actuate said first andsecond hydraulic motors for independently effecting operation of theirrespective actuating functions; e. a plurality of braking systemsoperably controlled by said tank supported components and operablyinteracting with each other, one of said braking systems beinghydraulically responsive to forming of an oil trap thereto, another ofsaid braking systems being dynamically responsive to reduction inhydraulic supply pressure within a closed hydraulic loop thereto, andstill another of said braking systems being mechanically operable andcomprising a pair of brake shoes movable into and out of brakingrelation with a braking surface and a hydraulic unit operably connectedto said brake shoes and effective when energized to actuate said shoestoward said braking relation; and f. flow control means introducing acontrolled time delay in energizing said hydraulic brake unit followingoccurrence of events requiring said mechanical braking system to beactuated.